Effects of One Evening Dose of 3 mg Eszopiclone on Next Day Driving Ability

Inclusion Criteria: * Aged between 18 and 55 years inclusive * In good health as determined by a medical history, ECG, haematology, blood and urine biochemistry and physical examination by the doctor * Diagnostic and statistical manual of mental disorders, defined primary insomnia * A body mass index greater than or equal to 18 and less than or equal to 30 * Registered with a general practitioner (GP) * Hold a full current driving licence for at least one year, and be regular car drivers Exclusion Criteria * The use of any other medication during the study with the exception of oral, transdermal, IUDs (progestogen only contraceptive e.g. Mirena), or depot contraceptives, non-steroidal analgesics (e.g. ibuprofen), and paracetamol. A 7-day washout period is required for any patient currently receiving prescription or non-prescription sleep medication. * Diagnosed sleep disorder or confirmed symptoms other than primary insomnia (e.g. restless leg syndrome, sleep apnoea) * Significant history of mental illness, significant drug allergy, malignancy or chronic drug abuse (including alcohol) * Any subject with known hypersensitivity to any of the study treatments * A sleep/wake cycle other than primary insomnia (e.g. shift work) liable to prejudice the results of the study * Pregnant or lactating females, and females of child bearing potential not using effective contraception * Patients who habitually smoke more than 5 cigarettes per day * Caffeine consumption of more than 5 cups or glasses per day * History of alcohol or drug dependence or intake of more than the equivalent of 14 units of alcohol per week for females and 21 units per week for males * Current participation in another clinical trial, or participation in a clinical trial within the last 90 days